[Q] S4 Active Black Screen Problem

Hello Guys. My problem is like this. Yesterday morning My S4 Active was functioning well but suddenly the screen went off and all the other things worked. I tough removing the battery and putting back on was going to resolve my problem but it does not. All other things seems to work well. The phone rings, vibrates, and led works. I opened the phone and cleaned all contacts and elements on the board with an electronic cleaner and a small brush. Not the first time I opened a phone. I want to know has anyone else has experienced this issue. What must be wrong with this phone. Is something wrong with the screen or there must be something with the board? Can i try anything to repair the screen. It seems like the screen is not getting power. Thank you

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